1. Statement of the Technical Field
The inventive arrangements relate generally to the transmission of data in a synchronous optical network, and more particularly to a method for improved utilization of certain undefined overhead data bytes in an otherwise defined data frame.
2. Description of the Related Art
The SONET (Synchronous Optical Network) telecommunications standard defines a set of signals for optical telecommunications data transport. The SONET standard provides a number of Data Communication Channels (DCCs) each having a different capacity for carrying management data across the network. This is accomplished by defining a base level signal having a lowest data carrying capacity, and using a byte-interleaved multiplexing scheme to generate higher level signals with larger data carrying capacity. In the SONET standard, the base level signal is generally referred to as the Synchronous Transport Signal level-1 (STS-1). Higher level signals are integer multiples of this base level signal and are generally referred to as STS-N signals. The byte-interleaved multiplexing scheme defined by the SONET standard provides that each STS-N signal is composed of N STS-1 signals that have been interleaved together to form the higher level transport signal.
Each STS-1 frame is divided into two main areas. These include a transport overhead area and a synchronous payload envelope (SPE) area for the transmission of payload data. The transport overhead area as defined by the SONET standard includes a number of Data Communication Channel (DCC) bytes that are used to form message channels for transporting management traffic. For example, the section DCC channel bytes can be used for operations, administration, and maintenance of section-terminating equipment. Similarly, line DCC bytes are used to form a message channel for control, monitoring, and administration of line-terminating equipment.
Notably, the existing SONET DCC channels are insufficient for transporting the volume of management traffic needed by net-centric, highly secure, converged networks. The capacities of existing defined SONET Data Communications Channels (DCC) are simply insufficient. For example the capacity of the section DCC is only 192 Kbps. Similarly, the capacity of line DCC is only 576 Kbps. The alternative to DCC is to transport management traffic in the SPE area that comprises the SONET payload. However, this robs payload bandwidth and decreases end-user data throughput. These are significant disadvantages where network centricity is increasing the demand for greater throughput of end-user data.